Diagnostic and Prognostic Utility of the Extracellular Vesicles Subpopulations Present in Pleural Effusion

Our plain-English summary of Diagnostic and Prognostic Utility of the Extracellular Vesicles Subpopulations Present in Pleural Effusion, by J. Javadi, A. Görgens, H. Vanky, et al (Biomolecules, 2021).

The study

• Authors: J. Javadi, A. Görgens, H. Vanky, D. Gupta, A. Hjerpe, S. El-Andaloussi, D. Hagey, K. Dobra
• Journal: Biomolecules
• Published: 2021;11(11)
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Extracellular vesicles (EVs), comprising exosomes, microvesicles, and apoptotic bodies, are released by all cells into the extracellular matrix and body fluids, where they play important roles in intercellular communication and matrix remodeling in various pathological conditions. Malignant pleural mesothelioma (MPM) is a primary tumor of mesothelial origin, predominantly related to asbestos exposure. The detection of MPM at an early stage and distinguishing it from benign conditions and metastatic adenocarcinomas (AD) is sometimes challenging. Pleural effusion is often the first available biological material and an ideal source for characterizing diagnostic and prognostic factors. Specific proteins have previously been identified as diagnostic markers in effusion, but it is not currently known whether these are associated with vesicles or released in soluble form. Here, we study and characterize tumor heterogeneity and extracellular vesicle diversity in pleural effusion as diagnostic or prognostic markers for MPM. We analyzed extracellular vesicles and soluble proteins from 27 pleural effusions, which were collected and processed at the department of pathology and cytology at Karolinska University Hospital, representing three different patient groups, MPM (n = 9), benign (n = 6), and AD (n = 12). The vesicles were fractionated into apoptotic bodies, microvesicles, and exosomes by differential centrifugation and characterized by nanoparticle tracking analysis and Western blotting. Multiplex bead-based flow cytometry analysis showed that exosomal markers were expressed differently on EVs present in different fractions. Further characterization of exosomes by a multiplex immunoassay (Luminex) showed that all soluble proteins studied were also present in exosomes, though the ratio of protein concentration present in supernatant versus exosomes varied. The proportion of Angiopoietin-1 present in exosomes was generally higher in benign compared to malignant samples. The corresponding ratios of Mesothelin, Galectin-1, Osteopontin, and VEGF were higher in MPM effusions compared to those in the benign group. These findings demonstrate that relevant diagnostic markers can be recovered from exosomes.

In plain English

This laboratory study from Karolinska Institutet in Stockholm, Sweden, examined tiny cell-released particles (extracellular vesicles) and dissolved proteins in 27 pleural effusions (fluid from around the lungs). Nine came from malignant pleural mesothelioma (MPM), 12 from metastatic lung adenocarcinoma, and 6 from benign conditions. The authors noted that three of the mesothelioma effusions came from the same patient at different times. The study did not measure asbestos exposure. The fluid was separated by centrifugation into apoptotic bodies, microvesicles, exosomes and the remaining fluid. Six proteins, including mesothelin, were at significantly lower levels in exosomes than in the remaining fluid. When each protein's measured concentration was split between only two fractions, exosomes and the remaining fluid, exosomes held 25.40% of mesothelin in mesothelioma effusions, 7.50% in adenocarcinoma and 10.30% in benign effusions. For angiopoietin-1 the exosome portion was 33.50% in mesothelioma and 81% in benign effusions. The article reports no statistical test for these group comparisons. The authors concluded that galectin-1, mesothelin, osteopontin and VEGF, which were higher, and angiopoietin-1, which was lower, in mesothelioma exosomes than in benign ones can be diagnostic markers for mesothelioma.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study of pleural effusion samples (biomarker analysis using centrifugation, Western blotting, nanoparticle tracking, bead-based flow cytometry and Luminex immunoassay)
• Who was studied: 27 pleural effusions collected at Karolinska University Hospital, Stockholm: malignant pleural mesothelioma (n = 9), metastatic lung adenocarcinoma (n = 12), benign reactive mesothelial proliferations (n = 6). Three of the mesothelioma effusions came from the same patient at different time points. Collection dates are not given.
• Exposure: Not studied. No asbestos exposure was measured. The study analysed extracellular vesicles and 10 proteins in pleural fluid.
• Main results:
  • Exosome fractions were measured in 14 patients (five benign, five adenocarcinoma, four mesothelioma). Particle sizes ranged from 30 to 600 nm. Mean concentrations were 3.8 × 10^6 particles/mL for mesothelioma, 3.1 × 10^6 for adenocarcinoma and 3.5 × 10^6 for benign patients.
  • Surface-marker profiling found the benign effusion least complex. The mesothelioma effusion was the most complex but had the lowest levels of the EV tetraspanins.
  • Across mesothelioma, adenocarcinoma and benign samples, galectin-1, mesothelin, osteopontin, VEGF, MMP-7 and HGF were significantly lower in exosomes than in the supernatant (two-tailed t-test, p at or below 0.05). NRG1-β1, angiopoietin-1, TIMP-1 and syndecan-1 showed no significant differences.
  • Table 1 splits each protein's measured concentration between exosomes and supernatant only; other fractions are not included. On that split, osteopontin, galectin-1, mesothelin and VEGF were proportionally higher, and HGF and SDC-1 lower, in exosomes from mesothelioma patients than in those from adenocarcinoma and benign patients. The exosome portion of mesothelin was 25.40% for mesothelioma, 7.50% for adenocarcinoma and 10.30% for benign effusions. For VEGF it was 12.30% for mesothelioma and 0.00% for both other groups. No statistical test is reported for these comparisons.
  • On the same exosome-versus-supernatant split, the exosome portion of angiopoietin-1 was 81% in benign effusions, 49.60% in adenocarcinoma and 33.50% in mesothelioma.
• The authors' conclusion: The authors concluded that galectin-1, mesothelin, osteopontin and VEGF (higher) and angiopoietin-1 (lower) in exosomes from mesothelioma patients, compared with benign patients, can be diagnostic markers for mesothelioma. They also reported differences in exosome surface proteins between mesothelioma and adenocarcinoma.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Pleural Mesothelioma, Asbestos Exposure, Adenocarcinoma, Pathology, Cytology, Mesothelin, Osteopontin.

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• Proteome screening of pleural effusions identifies galectin 1 as a diagnostic biomarker and highlights several prognostic biomarkers for malignant mesothelioma — F. Mundt, H.J. Johansson, et al. (2014)
• Ferroptosis-dependent extracellular vesicles from macrophage contribute to asbestos-induced mesothelial carcinogenesis through loading ferritin — F. Ito, K. Kato, et al. (2021)
• Extracellular Vesicles Isolated from Malignant Mesothelioma Cancer-Associated Fibroblasts Induce Pro-Oncogenic Changes in Healthy Mesothelial Cells — T. Chernova, S. Grosso, et al. (2022)
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